I need help with this problem

Answer:
[tex]4 \: \: ft[/tex]
Step-by-step explanation:
[tex]64 = x \times x \times x \\ {x}^{3} = 64 \\ x = 4[/tex]
to check whether the answer correct or wrong
[tex]x \times x \times x \\ 4 \times 4 \times 4 \\ 16 \times 4 \\ = 64[/tex]